Source : Webster's Revised Unabridged Dictionary (1913)

Abracadabra \Ab`ra*ca*dab"ra\, n. [L. Of unknown origin.]
   A mystical word or collocation of letters written as in the
   figure. Worn on an amulet it was supposed to ward off fever.
   At present the word is used chiefly in jest to denote
   something without meaning; jargon.

Source : WordNet®

abracadabra
     n : gibberish and nonsense